Going to a b16 crank and custom rods isn't really necessary, you can use the stock rod length and crank of the GSR and get great numbers. I've seen GSRs resleeved to 84-85 mm to make it about a 2 liter, and they make great power. A good set of cams, springs and retainers, skunk2 manifold, high compression pistons, a good port & polish job, balanced rotating assembly, and you'll have an all motor monster. Check out dyno charts of 2.0L vtec motors here, http://www.importreview.com/d_2.0.html and see what kind of numbers you can put down.